Self-locking setscrew



March 17, 1953 w KLOOZ SELF-LOCKING SETSCREW Filed Oct. 30, 1950 nvvawron PAUL w ALOOZ W M A ATTORNEYS Patented Mar. 17, 1953 r. j I-CEI 17 SELF- ING SETSCREW" BaulfTW-zt Kl'ooz, West;- Hartford, Conn., assignor tmTherHclb-Kmme Screw: (lornomtioni.. Elme wood; sebum, ascorporationrot Gonnecticutap licationetonated 1950; -Serial"No:'1*92,975

lsGlaim. (Cl. filer-7.0)

'-Thecpresmtinventionarelatesz-toasetscrews and more particularly toa novel and improvedcons structionior the nose-portion of asetscrew which provides the setscrew with new and unexpected operating characteristics:

The -primary function of assetscrew f the type ref e'rred to -here: is to fix the-relatitespositiorr of twomembersewhich are otiierwise movabl rela titewto other: Tiiesetserew usually is threadably received ma tapped opening of one crane-memes.- and' turned? until-it's noseengages with substantial pressure against the second member. When so employed the-pressure on the one-hand betweenthe threads of the set- Sc'rew and -thosewf the tapped" opening in the firstmember; and onthe-other'hand betweenthe noseofthe setscrewand thesecond member usually sefs'up'sufii'cient frictional resistance to prevenfi any-movement of the- 'membersrelative to thesetscrew and toeachother: Wherethe-second membert'is'movable-in such fashion that the surfacethereofengageable by the nose of thesetscrew may move laterally: by theaxis-- of the setscrew; it frequently the practice-to provide anoseiconstructi'orr in thesetscrew-in the nature Ufa pointwrcup which: will imbedri't'sel'fin" the surface-of the second" memberand-thusprorvide additional resistanceto the lateral" movement referred'tot' When azsetscrew' is turned into. rawwith suffrcienttpressure tolockth'e membersto'gether; the members and thesetscrew'are' frequently referred to in'ttheart asi'bein fseaiedz AS'IOTIB'fflS the niembersiremainf infs'ealedreiatiomi; e2; Withoutfany;reiative:'mcvementbetweeirthemembers amijithe' setscrew; the 'effiect'rvenessl: of. the setscrew is ata maximumi but"v any movement-tor the members or the s'etscrew Causihgja break in thez."se'al "rapidly diminishes. theeflectiveness of the-setscrew;v Asa general rule; ,suffi'cient'vibration,..,etc., owilIjibe'. present'fto' back up the setscrew to disengage the membersionce; theinitiahs'eal" has been broken.

As willbe apparent1a frequent cause of'the breaking of the; seal will be a siight" turning movement" of"th'e setscrew; Accordingly, many attempts have been made heretofore in theart toprovide some meansv for interlocking; the ,nose of. the setscrew with the member with" which it ispengaged." Such means have generally taken the form ofcuttineorjmillingj devices of various typesprovidect in then'ose ofthe setscrew which operatetocut projections, injthe'engagedmember. The: objectis to. cut thesuriace of the engaged memberteform thedesired projectionswithout completelysevering thez same so thati'someeintere engagement between the proj eotions and;:the.sete

usually are severed to some extent, particularly;

when the setscrew is backed out 1 of engagement; and this is particularly disadvantageous: when the setscrew' is used with machinery where; the presence of loose metallic particles can cause damage; Furthermore; the effectiveresist'ancelof projections which: are cut. in: this manner" even though not entirely severed is relatively weak and, therefore, doesnot create any material stabilizing force in addition to-that alre'ady'provided by friction. This is particularly true where: the provision of' cutting means: in. the nose'of'the setscrew diminishes theefiective area offricztionai contact? Furthermore, such modified" arrangements of the nose of theset-screw have been diflicui'tand expensive to fabricate so that the costof providing the so-called self-locking feature' far exceeds the very limited value and'efi'ectiveness-of these prior art constructions;

It is a principal aim of the present invention to provide a modified nose construction for a setscrew which willcausethe engagement of the nose of the setscrew with a metallicmember to form a true interIock' creating substantial resistance toreverse or disengaging turning of the setscrew;

A-*further-aim+of the invention is to provide a modified nose construction forasetscrewwhich will" create an interlocking engagementwith a metal-lic member-by -a-rmolding or-swa-ging action which. Willnot result inv undesirable cutting or severing of" metallic projections in themember and which will' inter' en'gage with the deformed or swaged portionof'fthemetallic"member-to"sub stantially resist relative turningmovement;

A further aim of the invention is to-provide such a desired modification of'the noseconstructionof" asetscrew which can" b'e'easi'l'y and'inexpensively manufactured" with the-result that setscrews" having the improved" characteristics referred to can be made at a negligible; if any, increase in cost and" can be easily fabricated without requiring" expensive" and difii'cuitmanufacturingoperations:

Other objectswill b'e'in part obvious; and in part poi'nted'out'more' in detail hereinafter:-

The invention accordingly" consists in the' features" of construction; combination" of elements and arrangement of parts which'will be exem'plfnecriir the construction hereaftersetforth' and the scope of the application of which will be indicated in the appended claim.

In the drawings:

Figure 1 is a side elevational view of a setscrew embodying the present invention.

Figure 2 is a bottom plan View of the screw shown in Figure 1.

Figure 3 is a vertical cross-sectional view of the screw shown in Figure 1 taken on the line 3--3 of Figure 2.

Figure 4 is a vertical cross-sectional View similar to Figure 3 and showing the setscrew in operative relationship with two relatively movable members.

Figure 5 is a cross-sectional view taken along the line 5--5 of Figure 4 and showing the interlocking deformation of the member engaged by the nose of the setscrew.

Referring to the drawings, a setscrew embodying the present invention'is shown, generally, by reference letter A and it includes a generally cylindrical body Ill provided with the usual external threads I2. Any suitable means may be provided to permit turning of the setscrew in accordance with the usual practice. In the exemplary setscrew A shown in the drawin the means for permitting turning of the setscrew is a polygonal socket I3 at the upper end of the setscrew for the insertion of a turning tool. The nose of the setscrew at the end opposite from the polygonal socket I3 is denoted generally by reference numeral I4.

Referring to Figure 4 of the drawings, the setscrew A is shown threadably received in a tapped opening 28 in a first member B with its nose portion I4 engaging a relatively movable second member C. As will be readily understood, the setscrew A is turned inwardly as permitted by its threaded engagement with the tapped opening in member B and its nose portion I4 engages the member C with a combined axial and rotational movement.

In order that the engagement of the nose portion of the setscrew may form an inter-locking engagement with the surface of the member C in accordance with the invention, I have found that the nose portion It may be formed by providing a pyramidal recess I5 in the nose end of the blank from which the setscrew is formed, such as by punching the same with a punch having a pyramidal head and then chamfering the nose portion to form an outer surface It of generally frusto-conical shape.

By so forming the nose portion of the setscrew, it will be observed that there is formed an annular cutting edge consisting of a sereis of annularly arranged flutes or waves 11. This cutting edge is found to be particularly effective for cutting an annular groove in the member C when the setscrew is turned into engagement therewith with sufiicient force or torque.

Immediately above the cutting edge provided by the flutes or waves the nose portion rapidly increases in thickness, being bounded on the outside by a frusto-conical surface I6 and bounded at its interior surface by a plurality of generally triangularly shaped chordally arranged facets I8. Accordingly, as the cutting edge descends into the member C, as a result of the turning movement of the setscrew, the metal of the member C is.

first cut or severed in an annular line 2| and then the metal on either side of the cut or severance line is forced away from the cut by the descending nose of the setscrew. This causes an annular rim or ridge 22 to be formed in the metal of the member C extending about the periphery of the nose of the setscrew and at the same time compresses the metal within the pyramidal recess of the nose portion. The final result is that when the setscrew is turned with sufficient torque the metal within the pyramidal recess of the nose portion of the setscrew is compressed to such an extent that it will flow and mate with the interior surface or facets of the setscrew nose. This condition is best shown in Figure 5 of the drawings, it being noted that a frusto-pyramidal projection 23 has been formed interiorly of the annular cut or groove 2| in the surface of the member C which corresponds in shape to the pyramidal recess I5 in the nose of the setscrew whereby the recess I5 operates as a polygonal socket for engaging on the polygonal projection 23, thus great- 1y resisting any reverse turning of the setscrew.

The effectiveness of the interengagement of the frusto-pyramidal projection 23 with the pyramidal recess I5 is substantial and greatly increases the utility and successful operation of the setscrew. As will be apparent, reverse or loosening turning of the setscrew after it has been set in place can be accomplished only by deforming the corners of the projection 23. For example, in a hexagonal socket, the ratio of the largest diameter (across the corners) to the smallest diameter (across the flats) is of the order of 1.1547 to 1. There is thus provided a considerable re-, sistance or holding force which is a material ad-, dition to the resistance to movement occasioned by friction alone.

It will be noted that in the exemplary embodiment shown in the drawings the pyramidal recess has been shown as hexagonal, although it will be realized that a greater or fewer number of sides could be employed. In general, when the number of sides is increased the pyramidal recess more nearly approaches a conical shape, thus decreasing its effective interlocking engagement with the member C. Conversely, when the number of faces or sides is decreased, the amount of swaging or deformation of the metal of member C is increased, with the result that the setscrew becomes increasingly difiicult to turn. In general, a six-sided pyramidal recess I5 appears to be a preferred compromise as it provides a desired ease of turning with adequate interlocking.

As described above, there has been provided, in accordance with the invention, a novel construction for the nose portion of a setscrew which can be fabricated with a minimum of effortand at extremely low cost and which, at the same time, will provide a true interlocking between the surfaces of the setscrew nose and the workpiece which effectively aids in overcoming the tendency of the setscrew to turn relative to the workpiece when subjected to vibrations, and the like.

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the language used in the following claim is intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

I claim as my invention:

A setscrew comprising an externally threaded 6 interlocking the nose of the setscrew with the piece.

PAUL W. KLOOZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 10 Number Name Date 2,201,087 Hallowell May 14, 1940 2,314,274 Hallowell Mar. 16, 1943 

